Extrinsic electromagnetic chirality in all-photodesigned one-dimensional THz metamaterials

TL;DR

This paper demonstrates that all-photodesigned, sub-wavelength patterned semiconductors can exhibit reconfigurable extrinsic electromagnetic chirality in the THz range, enabling new tunable polarization control devices.

Contribution

It introduces a novel method for creating reconfigurable, chiral metamaterials using photo-induced carrier patterns on semiconductors for THz applications.

Findings

Photo-induced patterns exhibit 1D geometrical chirality.

Extrinsic chirality is fully reconfigurable via optical illumination.

Potential for reconfigurable THz polarization devices.

Abstract

We suggest that all-photodesigned metamaterials, sub-wavelength custom patterns of photo-excited carriers on a semiconductor, can display an exotic extrinsic electromagnetic chirality in terahertz (THz) frequency range. We consider a photo-induced pattern exhibiting 1D geometrical chirality, i.e. its mirror image can not be superposed onto itself by translations without rotations and, in the long wavelength limit, we evaluate its bianisotropic response. The photo-induced extrinsic chirality turns out to be fully reconfigurable by recasting the optical illumination which supports the photo-excited carriers. The all-photodesigning technique represents a feasible, easy and powerful method for achieving effective matter functionalization and, combined with the chiral asymmetry, it could be the platform for a new generation of reconfigurable devices for THz wave polarization manipulation.